A defined skin test for detecting M. tuberculosis (Mtb) could have significant advantages over PPD in terms of sensitivity and specificity. Such a test could be used in persons infected with HIV, and could be used to distinguish Mtb from BCG immunization. We have identified new antigens of Mtb that stimulate human PBMC in vitro, and that elicit positive DH responses in the guinea pig model of tuberculosis. The goal of this proposal is to evaluate these antigens for the development of an intradermal skin test for the specific and sensitive detection of M. tuberculosis infections. PROPOSED COMMERCIAL APPLICATIONS: The market for a tuberculosis skin test is very large, exceeding $50,000,000 if it would be used to replace PPD. If it is used in a subset of infected individuals, such as HIV infected, the market would be smaller, but should still exceed $25,000,000 per year.